The present invention relates in general to abrasive material separation systems. In particular the present invention relates to a mobile apparatus and process for collecting and recovering abrasive grit material from blasting material containing contaminants created during a pressure blasting process.
Abrasive blasting of steel structures, such as highway bridges, is a necessary step in maintenance of structures. One particular problem encountered with structures such as bridges is that the past painting history of the structure typically will include a lead based paint. The lead dust is considered quite toxic and is increasingly regulated. An approach to controlling the environmental problem associated with the lead dust is to recover all the abrasive grit and waste material associated with the pressure blasting process. If the abrasive grit material is not separated from the lead dust and other blasting site waste, an undesirably high quantity of hazardous waste remains for subsequent disposal. A mobile apparatus having an abrasive grit material recovery system provides the process for accomplishing this entire task.
In the past devices for the recovery of abrasive grit blasting material have used magnets, rotary brooms, mechanical conveyors and elevators, as well as induced air currents to recover and recycle the abrasive particles with varying degrees of success. The prior devices for recovering abrasive grit material created during pressure blasting have had common limitations.
The first limitation is that the devices have tended to be heavy and bulky in nature and therefore not readily transportable to a job site. More particularly the vertical elevation of the devices have often interfered with passage beneath structures, such as highway and railroad bridges. A second limitation is that the recovery of the abrasive grit blasting material is often undertaken in an environment at substantially atmospheric pressure with open transfer between stages. This may allow grit and dust to be expelled into the environment which produces an undesirable high quantity of pollution. A third limitation is that the devices have generally not been integrated, and require multiple pieces of equipment to collect and process the material created by pressure blasting.
Even with the variety of earlier designs, there remains a need for an integrated mobile apparatus for collecting and recovering abrasive grit material that minimizes the grit and dust expelled into the environment during the recovery of the abrasive grit material, yet has a low profile design to avoid interfering with structures, such as highway and railroad bridges. The present invention satisfies this need in novel and unobvious ways.